1. Field of the Invention
This invention relates to an oil seal means of a rotary piston engine, and more particularly, a linear oil seal means principally intended to obtain an oil scraping effect.
2. Description of the Prior Art
A rotary piston engine has generally a center housing having a trochoidal inside surface and at least two side housings closing opposite open ends of said center housing to define a chamber therein, in which is eccentrically rotated a polygonal rotor, wherein the oil and gas tightness between said rotor and said side housing is maintained by an oil seal means composed of an oil seal ring mounted in an annular oil seal groove formed as a cut in a side wall portion of the rotor and urged against the inner wall of the side housing under the action of a spring force. An annular elastic means such as an O-ring is adapted to intercept the fluid passage crossing an annular space left between the wall of said annular oil seal groove and said oil seal ring.
In the oil seal means of the abovementioned structure, the axial outer end face of the oil seal ring is so shaped that it contacts with the inside surface of the side housing along the radially inside peripheral portion thereof and extends therefrom as inclined towards the radially outside portion thereof thereby defining a wedge space opening towards the radially outside region of the rotor between the inside surface of the side housing and the rotor, whereby it is so adapted that the oil flowing radially inwardly of the rotor by being urged by the gas pressure in the operating chamber is caught by the wedge membrane effect and recovered and that the oil flowing radially outwardly under pressure from the side of the eccentric shaft is scraped to prevent leakage of oil into the operating chamber. However, the oil recovering function made by the conventional oil seal means is only accomplished in a region located within an envelope of loci drawn by said annular oil seal ring during the rotation of the rotor. Therefore, by employing the conventional oil seal means, it is difficult to recover the oil which has moved out of said envelope, oil usually flows up to a corner seal and then enters into the combustion chamber through a clearance of the corner seal as well as that apex seal which burned therein, whereby there occurs much loss of oil and movability of the sealing means is affected by oil sludge.